Catalyst and method for converting low molecular weight paraffinic hydrocarbons into alkenes and organic compounds with carbon numbers of 2 or more

Abstract

A catalyst and process for formation of hydrocarbons having carbon numbers of two or greater, the result of both oxidative coupling of methane (“OCM”), and other reforming reactions of OCM end products. An OCM catalyst has a structure represented by formula ABTiO3, wherein A is samarium or tin, B is barium; the reforming catalysts a composition represented by formula XYZ, wherein X is a metal from Group IA, Group IIA or Group VIIIA, or not present, Y a metal from Group VA, Group VIA, Group VIIA or Group VIIIA, Z chosen from oxygen, silica, silicalite and alumina. The inventive catalyst comprises an OCM catalyst and a reforming catalyst blended together; when used in a reactor effects an increased yield of hydrocarbons having a carbon number greater than 2 (in excess of 27%-30%, first pass rate of methane conversion about 50%) than occurs under OCM conditions alone.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of United States Provisional Application for Patent, Ser. No. 60 / 713,990, filed 2 Sep. 2005, the contents of which are hereby incorporated by reference herein in their entirety.FIELD OF THE INVENTION [0002] The present invention relates to novel catalysts and processes for producing alkenes, carbon oxides, hydrogen and other organic compounds with carbon numbers of 2 or more from alkanes (also referred to herein as paraffinic alkanes) such as methane (CH4) that are found as the major component in most natural gas streams. Once methane is converted to higher carbon number alkenes, such as ethylene, there are existing commercial technologies to further react the products of the present invention into liquid hydrocarbons, plastics and other valuable commodities. More particularly, the invention relates to a combination of oxidative and reducing / reforming catalyst components used in combination to control...

AI Technical Summary

Benefits of technology

[0037] An advantage of the oxidative reforming process is a reduction in the amount of undesirable coking. Use of the oxidative reforming catalyst promotes oxidative coupling of methane and other reactions with first pass rates of methane conversion of approximately 50% and yield of organic compounds with carbon numbers greater than 2 that exceed 27%, and in some instances, exceed 30%.

Problems solved by technology

Most natural gas is situated in areas that are geographically remote from population and industrial centers making it difficult to utilize these gas resources.

The costs and hazards associated with the compression, transportation, and storage of natural gas make its' use economically unattractive.

This wasted resource also contributes to global carbon dioxide emissions and to undesirable global warming.

The two step process, syngas formation followed by reforming reactions, such as methanol synthesis, requires two reactor stages and is inherently inefficient due to heat and material losses as well as the need for additional capital equipment for processing and separating the resulting gas and liquid streams.

The highly exothermic reactions of partial oxidation have made it inherently difficult to control the reaction temperature in the catalyst bed.

This is particularly true when scaling up the reaction from a micro reactor to a larger scale commercial reactor unit due to the additional heat generated in large reactors and the limited heat transfer available in a larger reactor.

Furthermore, oxidation reactions are typically much faster than reforming reactions.

The large volumes of expensive catalysts needed by prior art for catalytic partial oxidation processes and the need for a separate reforming operation have placed these processes generally outside the limits of economic justification.

Such high conversion and selectivity must be achieved without detrimental effects to the catalyst, such as the formation of carbon deposits (“coke”) on the catalyst, which severely reduces catalyst performance.

This often, however, results in coke formation on the catalyst.

The noble metals have been used as catalysts for the partial oxidation of methane, but they are scarce and expensive.

Less expensive catalysts such as nickel-based catalysts have the disadvantage of promoting coke formation on the catalyst during the reaction, which results in loss of catalytic activity.

Previous inventions utilizing oxidative reactions have also been limited in the size of reactors and amount of catalyst used due to the need to rapidly extract heat to avoid the formation of undesirable combustion products (primarily CO2 and H2O).

Previous inventions have also shown poor catalyst life and / or low conversions and yields of desired reaction products.

Previous inventions have relied mainly on partial oxidation of methane that results in high levels of undesirable carbon oxides and water or dehydrogenation type mechanisms that result in carbon formation and coking of the catalyst.

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